Electric discharge device



Dec. 27, 1938. c MIYAUCHf 2,141,312

ELECTRIC DISCHARGE DEVICE Filed May 1, 1935 Inventor: ChU 'i Miyauchi,

is ttorney Patented Dec. 27, 1938 UNITED STATES PATENT OFFIQE ELECTRIC DISCHARGE DEVICE York Application May 1, 1935, Serial No. 19,281 In Japan May 25, 1934 9 Claims.

The present invention relates to electric discharge devices and more particularly to supports for mounting the electrodes within such devices.

During the evacuation of electric discharge tubes, it is customary to subject the electrodes to a high temperature heat treatment by means of a high frequency coil placed around the envelope. The coil serves to induce currents in those metal parts which are perimetrically complete and conlO stitute a closed secondary Winding or turn. Ob-

viously, unless the position of the coil is closely regulated so as to select the metal parts which are intended to come within its influence, and sometimes even then, particularly if the metal parts are positioned close together, circulatory currents are induced in the metal members which support the electrodes from the glassware. These members usually constitute collars or rings of resilient metal which are clamped, or in any other manner secured. to one or more reentrant stems of the envelope. These collars are usually constituted of metal throughout their entire periphery and when brought either intentionally or accidentally within the field produced by the high frequency coil, become heated, which in turn may cause the glass stem which they embrace to crack.

An object of the present invention is to provide an improved electrode support of the ring or collar type which will not be substantially affected by high frequency currents induced in the electrodes during manufacture of the tube, regardless of the position of the coil. In brief, my invention contemplates the use of an improved 5 collar or ring which is electrically incomplete about its perimeter and hence cannot offer a closed circuit for induced currents. The invention will be better understood when reference is made to the drawing in which Fig. 1 shows an 40 elevational view of an electrical discharge device provided with electrode supports improved in accordance with the present invention, while Fig. 2 is an enlarged end view of the improved support.

Referring to Fig. 1, numeral 1 designates an evacuated envelope which may or may not contain gas or vapor-producing material, the envelope terminating' at the ends in reentrant stems 2, 3. An electrode assembly is supported between these stems by means of collars 4, 5. This assembly may consist of a hemispherical anode 6 of the usual construction, made of metal or of carbon, and suspended from the upper collar 5 by rods 1 which are secured to the electrode in any suitable manner. A conductor 8 may be taken from the anode through the reentrant stem 3.

The cathode 9 is of the well-known indirectly heated type provided with one or more perforated heat shields. As shown, the cathode extends well into the hollow space or bowl formed by the anode. The cathode is conveniently supported from the lower stem 2 by means of two or more rigid rods E0 separated by a bridge member I I and secured to the lower collar 4 in any suitable and well-known manner. Leads 12 may be taken from each end of the heater within the cathode and from the cathode itself through the stem 2.

During the fabrication of a tube of this sort, it is necessary to denude the electrodes of cocluded gases and this is conveniently done by heating the electrodes while the tube is on the pump. For this purpose, a high frequency coil (not shown) is mounted about the envelope so as to surround the electrodes and since the electrodes constitute a closed secondary, currents are induced therein which serve to heat the electrodes to temperatures sufficiently high for evacuation purposes. It is apparent that during this procedure, the collars 4, 5 may also come within the influence of the high frequency coil and if they constitute a closed secondary, currents will also be induced therein. These currents may be sufiiciently large to heat the collars to high temperatures which in turn may cause the glass which they embrace to crack.

However, in accordance with the present invention, collars are provided which do not offer a closed circulatory path for currents and hence even when the collars are subjected to the influence of the high frequency coil, currents are not induced therein. and the collars remain relatively cool, at least not sufficiently heated to cause any cracking effect on the stems. As shown more clearly in Fig. 2, the improved collar consists of a ring of resilient metal which is provided with a gap I3. The collar at the gap terminates in a pair of juxtaposed extensions 14 which are adapted to receive one or more bolts l5. As shown, the shank of these bolts passes through one of the extensions l4 and is secured to the other extension by means of a nut I 6. The head ll of the bolt is provided with a slot 18 for convenience in turning the same and bears against the other of the two extensions. Interposed be tween the head and shank of the bolt, there is an annular Washer 19 of a refractory insulating material which serves electrically to insulate the bolt from one of the extensions [4.

It is clear that the improved collars 4, 5 may be tightened about the stems by turning the bolts l5 and notwithstanding the fact that the bolt is effective in drawing the two extensions together by closing the gap therebetween, the collar remains electrically incomplete, due to the inserted insulating material l9. Accordingly,even though the collars are positioned sufficiently close to the electrodes so as to come within the influence of the high frequency coil which surrounds these electrodes during fabrication of the tube, substantially no current will be induced in the collars and hence the latter will remain relatively cool under these conditions.

While I have shown one specific way in which the collar may be tightened by means of bolts without offering a circulatory path for induced currents, it is apparent that other ways of accomplishing this will readily occur to those skilled in the art.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electrical discharge device comprising an envelope terminating in a stem, electrodes in envelope, a support for one of said electrodes including a collar which embraces said stem, said collar being provided with a longitudinal gap whereby the collar is perimetrically incomplete, and insulated means for securing said collar to stem.

2. An electrical discharge device comprising an envelope terminating in a stem, electrodes in said envelope, a support for one of said electrodes including a collar which embraces said stem, said llar being provided with a longitudinal gap whereby the collar is perimetrically incomplete, and insulated means for drawing the ends of the collar together, thereby closing said gap and securing the collar to said stem.

3. An electrical discharge device comprising an envelope which terminates in a stem, a plurality of electrodes in said envelope, one of said electrodes being supported from said stem by means of a metal clamp ring which embraces the stem, said ring being provided with a non-metallic peripheral portion whereby the circulatory current path through said ring is interrupted, and means for securing said ring to said stem.

2. An electrical discharge device comprising an envelope terminating in a reentrant stem, electrodes in said envelope, a support for one of said electrodes including a collar which embraces said stem, said collar being provided with an insulated peripheral portion and terminating at said portion in juxtaposed extensions which are separated by a gap, means for drawing said extensions together whereby the collar is tightened on said stem.

5. An electrical discharge device comprising an envelope terminating in a stem, electrodes in said envelope, a support for one of said electrodes including a collar which embraces said stem, said collar having a longitudinal gap, the ends of the collar at the gap terminating in a pair of juxtaposed extensions, means for drawing said extensions together, said means including a portion which is insulated from one of said extensions.

6. An electrical discharge device comprising an envelope terminating in a stem, electrodes in said envelope, a support for one of said electrodes including a collar which embraces said stem, said collar having a longitudinal gap and terminating at the gap in a pair of juxtaposed extensions, a bolt secured to said extensions and adapted to be turned in order to reduce the width of said gap whereby the collar is tightened on the stem, said bolt being insulated at one end from said collar.

'7. An electrical discharge device comprising an envelope terminating in a stem, electrodes in said envelope, a support for one of said electrodes in cluding a collar which embraces said said collar being provided with a longitudinal gap, the ends of the collar at the gap being bent to form juxtaposed extensions, and means for drawing said extensions together whereby the length of the gap is reduced and the collar is tightened on the stem, said means including a bolt which passes through one of the extensions and is secured to the other of the extensions, and insulating inaterial extending over the entire contacting surface between the bolt and one of said extensions.

8. In an electron discharge device, a glass support, a metal collar surrounding said support, said collar being electrically open circuited at one point, and an electrode supported by said collar.

9. In a thermionic discharge device, an envelope with a reentrant stem, a metallic strap frictionally secured to the outer surface of said stem, said strap being bent outward at its ends and perforated at its ends to receive a belt, an insulating collar to center said bolt in said perforations and out of contact with the edges of said perforations, and an electrode supported from said strap.

CHUJI MIYAUCHI. 

